Vitest API

untestutils/vitest/plugin

Option	Type	Description
recipes	RecipeRegistry	From defineRecipes(..., import.meta.url)
recipesModule	string?	Rare path override
artifactsRoot	string?	Artifacts directory
session	string?	Isolate under .untestutils/sessions/<session>/ (shared with Playwright)
prewarm	string[]	Ids to prepare/start
browsers	HarnessBrowserName[]?	Default ['chromium']; multiple → injectTestProjects
coverage	boolean | CreateCoverageConfigOptions	Merge Vitest coverage

Also: createCoverageConfig(), createVitestProjects({ e2e, unit }), HARNESS_BROWSER_NAMES, normalizeHarnessBrowsers.

Session context is provide/inject (untestutils, untestutilsBrowser); env remains fallback for CLI/PW.

untestutils/vitest (specs)

Exports: test, describe, expect, useHarness, defineRecipes, fixtures (harness, page, goto, baseURL, request, browserName).

See Vitest guide.